Gas bag restraint systems exist which include a multi-stage inflator and a gas bag in flow connection therewith, the gas bag comprising a first and second fabric part, which are at least approximately congruent, at least one burst seam being provided which in its intact condition forms a fold as a result of which the volume of the gas bag is reduced as compared to a condition in which the burst seam is destroyed.
Such a gas bag restraint system allows to provide a restraint effect optimally adapted to the conditions in each case. In case of low vehicle speeds and/or light weight of the vehicle occupant to be restrained as well as in case of a small distance of the vehicle occupant from the cover of the gas bag, only a first stage of the inflator is activated so that only a relatively small amount of compressed gas is made available for deploying the gas bag. In this case the burst seam remains intact so that the gas bag is fully deployed despite the low amount of compressed gas made available. By contrast, in case of high vehicle speeds and/or heavy weight of the vehicle occupant to be restrained as well as in case of a large spacing of the vehicle occupant from the cover of the gas bag, several stages of the inflator are activated so that a relatively large amount of compressed gas is made available for deploying the gas bag, resulting in the destruction of the burst seam on deployment of the gas bag, thus enlarging also the volume of the gas bag to accommodate the larger amount of compressed gas.
The invention provides a gas bag restraint system including a multi-stage inflator and a gas bag in flow connection therewith. The gas bag comprises a first and a second fabric part which are at least approximately congruent, and a fabric strip which is stitched to an edge of the first fabric part and to an edge of the second fabric part. At least one burst seam is provided which in an intact condition forms a fold as a result of which the volume of the gas bag is reduced as compared to a condition in which the burst seam is destroyed. The fold formed by the burst seam is arranged in the fabric strip. This configuration permits a particularly simple and advantageous adaptation of the gas bag to specific requirements.
Advantageous configurations of the invention read from the sub-claims.